Spontaneous abortion occurs in 10% to 15% of all clinically recognised pregnancies. Chromosome abnormalities account for 65% to 70% of miscarriages, of which autosomal trisomy (Down’s Syndrome) is the most common. Chromosome testing of products of conception (POC) offers valuable information to both the provider and couple and can aid in future clinical management.
One study found only 8% of first-trimester miscarriages underwent chromosome analysis, but the majority of couples desire testing. These results often provide an explanation for the miscarriage and help couples cope with the emotional aspects of the pregnancy loss. Furthermore, chromosome testing in women with recurrent pregnancy loss offers cost savings by decreasing the need for other investigational studies to identify other cause.
The current gold standard of products of conception testing is with metaphase karyotype, which is typically performed by the cytogenetics department at each institution. However, this method has practical limitations, including the reliability of successful cell culture with failure rates ranging from 10% to 40%. A cytogenetic result of 46,XX, which occurs in 55% to 80% of cases, cannot exclude the presence of maternal cell contamination. In addition, prolonged culture may lead to culture artefacts, which may produce inaccurate results. Finally, due to the band resolution of this method, sub-microscopic deletions and duplications, typically less than 5 Mb, cannot be detected.
Newer molecular methods have offered novel techniques to analyze miscarriage specimens. These include single nucleotide polymorphism (SNP) microarrays and array comparative genomic hybridization (aCGH). These technologies offer faster results with higher resolution and minimal tissues requirements. Patients may also send their samples collected at home within 7 to 14 days of passing tissue.